1. Field of the Invention
The present invention relates generally to vehicle suspension systems. More particularly, the present invention relates to a rear wheel suspension assembly suitable for use in connection with off-road bicycles.
2. Description of the Related Art
Off-road bicycles, or mountain bikes, may be equipped with front and rear suspension assemblies operably positioned between the front and rear wheels, respectively, and the frame of the bicycle. Providing front and rear suspension on a mountain bike potentially improves handling and performance by absorbing bumps, and other rough trail conditions, which may be encountered while riding off-road. However, because mountain bikes are typically pedal-driven, i.e., use the rider""s power output to propel the bicycle, the provision of rear suspension, especially, may undesirably absorb a rider""s power output, resulting in wasted effort.
Accordingly, rear suspension systems commonly incorporated on engine-driven vehicles, such as motorcycles, have proven ineffective for use with pedal-driven vehicles, such as mountain bikes. In addition, because a mountain bike is propelled solely by power output from the rider, it is desirable that the rear suspension assembly be lightweight. Rear suspension systems of engine-driven vehicles commonly emphasize strength over weight and, therefore, have not been widely incorporated on mountain bikes.
Mountain bike rear suspension designs, utilizing multiple linkage members, are currently used and are often effective at isolating pedal-induced and brake-induced forces from acting on the rear suspension. However, one problem associated with prior mountain bike rear suspension designs involves placement of the rear shock absorber. Due to the relatively complex nature of common mountain bike rear suspension assemblies, the placement of the rear shock absorber has often precluded the use of a traditional triangular mainframe of the mountain bike. For example, typical rear shock placement has either precluded the use of a vertical seat tube member of the mainframe, or has been positioned within the internal space defined by the mainframe. As the down tube and the seat tube members of the mainframe have traditionally been provided with mounts, or bosses, for mounting of water bottle cages, many designs incorporating rear suspension assemblies have inhibited the use of one, or both, of the traditional water bottle cage locations due to the placement of the rear shock absorber.
Preferred embodiments of the present invention desirably inhibit pedal-induced forces and brake-induced forces from acting on the rear suspension while maintaining the use of a traditional triangular mainframe of the mountain bike. In addition, one end of the rear shock absorber is desirably positioned close to the axis of rotation of the rear wheel, or the hub axis. Accordingly, if an inertia valve is incorporated within the rear shock absorber, it may be positioned near the hub axis, where the greatest inertial forces are present. As a result, the sensitivity of the inertia valve is increased.
A preferred embodiment is a bicycle frame having a main frame portion and an articulating frame portion. The articulating frame portion including a pair of lower arms having a forward end and a rearward end. The forward ends being pivotally connected to the main frame portion at a first pivot axis. The articulating frame portion also includes a pair of upper arms having a lower end and an upper end, the lower ends being pivotally connected near the rearward ends of the lower arms at a second pivot axis. One of the rearward ends of the lower arms and the lower ends of the upper arms define a hub axis. The articulating frame portion additionally includes a link pivotally connected to the upper ends of the upper arms at a third pivot axis and pivotally connected to the main frame portion at a fourth pivot axis. A shock absorber is pivotally connected to either the main frame portion or the link at a fifth pivot axis and pivotally connected to the articulating frame portion at a sixth pivot axis, the sixth pivot axis being located near the hub axis.
A preferred embodiment is a bicycle frame including a main frame portion comprising a top tube, a seat tube and a down tube arranged in a generally triangular arrangement and defining a generally triangular space therebetween. A first water bottle mount is defined on the seat tube and faces the space. The first mount is sized and shaped to permit a first water bottle holder to be secured to the seat tube at the first mount. A second water bottle mount is defined on the down tube and facing the space. The second mount is sized and shaped to permit a second water bottle holder to be secured to the down tube at the second mount. The bicycle frame further includes an articulating frame portion comprising a pair of lower arms having a forward end and a rearward end, a pair of upper arms having a lower end and an upper end, and a link. The forward ends of the lower arms are pivotally connected to the main frame and the lower ends of the upper arms are pivotally connected near the rearward ends of the lower arms. The link is pivotally connected to the upper ends of the upper arms at a first end and pivotally connected to the main frame. A hub axis is defined by one of the lower ends of the upper arms and the rearward ends of the lower arms. A shock absorber is pivotally connected to either the main frame or the link at a first end and pivotally connected to the articulating frame portion near the hub axis at a second end.
A preferred embodiment is a bicycle frame including a main frame portion comprising a seat tube. An upper mounting bracket is connected to the seat tube and a lower mounting bracket is connected to the main frame. The frame also includes an articulating frame portion including a pair of lower arms having a forward end and a rearward end. The forward ends being pivotally connected to the lower mounting bracket. The articulating frame portion additionally includes a pair of upper arms having a lower end and an upper end, the lower ends being pivotally connected near the rearward ends of the lower arms. One of the rearward ends of the lower arms and the lower ends of the upper arms define a hub axis. A link is pivotally connected to the upper ends of the upper arms and pivotally connected to the upper mounting bracket. A shock absorber is pivotally connected to either the main frame portion or the link and pivotally connected to the articulating frame portion near the hub axis.
A preferred embodiment is a bicycle frame comprised of a main frame portion and an articulating frame portion. The articulating frame portion is comprised of a pair of lower arms having a forward end and a rearward end, the forward ends being pivotally connected to the main frame portion. The articulating frame portion also includes a pair of upper arms having a lower end and an upper end, the lower ends being pivotally connected near the rearward ends of the lower arms. One of the rearward ends of the lower arms and the lower ends of the upper arms define a hub axis. A link is pivotally connected to the upper ends of the upper arms and pivotally connected to the main frame portion. A shock absorber is connected to the bicycle frame and is arranged to provide a force resisting movement of the articulating frame portion with respect to the main frame portion, a first end of the shock absorber being pivotally connected to the articulating frame portion near the hub axis.